WHO Director-General Margaret Chan on January 4 (epa)
January 5, 2007 -- The new head of the World Health Organization has renewed the agency's warning that the world must keep up its guard against bird flu.

Margaret Chan, who took up her post on January 4, said a bird-flu pandemic would be devastating. Bird flu, which has ravaged poultry populations in Southeast Asia, has killed some 150 people in the last few years.

But experts fear that if it becomes more easily passed between humans, it could trigger a pandemic in which millions could die.